Alco Controls

Alco Controls
Electrical Control Valves
Electrical Control Valve Technology
Thermostatic expansion valves and mechanical
regulator valves have been used in the refrigeration
and air conditioning industry to control superheat
and refrigerant mass flow since its very beginning. As
today’s systems require improved energy efficiency,
tighter temperature control, wider range of operating
conditions and incorporate new features like remote
monitoring and diagnostics, the application of
electronically operated valves becomes mandatory.
Only they offer the controls performance necessary
to meet these needs.
Electrical control valves are actuators only. For
operation in a system they need sensors, valve drivers
and controllers, see next chapter.
EX2 is designed for pulse width modulation. It is
applicable to all common HCFC and HFC refrigerants
and for subcritical CO 2 applications and is used mainly
for refrigeration applications such as display cases.
The EX2 valve is a slide type solenoid valve with an
orifice for expansion. It is either completely open or
completely closed. One common valve body can be
combined with 6 interchangeable orifices to cover 7
capacity ranges.
EX4/EX5/EX6/EX7/EX8 consist of two main internal
assemblies, the valve and the stepper motor. The
stepper motor is located next to the electrical
plug and connected directly to the slide and cage
assembly of the valve. Similar to the technology used
in compressors, the motor is exposed to refrigerant
and lubricant and the materials used are identical
to the ones in compressor motors. The housing
of the motor and valve assembly is made from
stainless steel and fully hermetic, utilising exclusively
brazing and welding technologies and eliminating
all gaskets.
This design offers several technical advantages such
as proportional linear mass flow and a wide capacity
range.
A common feature of all ALCO electrical control valves
is the positive shut-off function, which eliminates the
need for additional solenoid valves.
Valve Selection
For EX2 the published table quotes capacities at 100%
duty cycle. i.e. valve open continuously. However, it
is recommended to operate the valve at partial load
(50-80%) to allow for system load fluctuations.
For EX4/EX5/EX6/EX7/EX8 and EXM/EXL all
published capacities are maximum and there are no
reserve capacities. Each valve should be selected for
the highest possible capacity of the system. A wide
range regulation (10 … 100%) with one slide orifice
for each valve is achievable.
To facilate valve dimensioning for other than the
standard conditions ALCO offers an Excel based
Selection Tool. This can be downloaded from
www.emersonclimate.eu.
Selection Table for Electrical Control Valves and applicable Controllers
Valve Function Capacity Feature Min. Main Application Applicable Controller
Type kW Evaporating
R407C Temperature °C Page Page
Heat pumps,
EXM Expansion
Uni polar stepper
s. data
5 .. 20.7
-30 Air Conditioning 7 customized
EXL Valve
motor driven
sheet
Close control
EX2 Exp. Valve 1.0 .. 18.7 PWM -40 Refrigeration 8 EC2 40
EX4 2 .. 17.4
EX5 5 .. 53 Heat pumps,
Expansion
Bi polar stepper
EC3-X.. Superheat Contr. 36
EX6
15 .. 126
-100 Refrigeration, A/C, 12
Valve
motor driven
EC3-3.. Cold room Contr. 43
EX7
35 .. 347
Water Chillers
EX8 100 .. 925
EX4 4.9
EX5 16
Capacity
Bi polar stepper
Hot gas bypass
EX6
37
-100
Control
motor driven
regulator
EX7
131
20 EXD-U.. Universal Contr. 37
EX8 399
EX6
3.9
Suction pressure /
Capacity
Bi polar stepper
EX7
14
-50 crankcase pressure
Control
motor driven
EX8 42 regulator
21 EXD-U.. Universal Contr. 37
EX5 18
EX6 Liquid Mass 43 Bi polar stepper Condensing pressure
-
EX7 Flow Control 153 motor driven
and liquid regulator
23 EXD-U.. Universal Contr. 37
EX8 463
EX6
11
Heat
Bi polar stepper Heat Reclaim
EX7
39
-
Reclaim
motor driven
applications
EX8 119
25 EXD-U.. Universal Contr. 37
A2.5.1/0810/E